specifying runtime env for JavaWebServer 2.0

I have got this particular problem. The JavaWebServer has got run-time environment Jre 1.1 I want to have JRE 1.2 as the run time environment. bcos we are using JAVA 2.0 specific APIs. Can you help me with where & How do I specify the Run Time Environment. For ur info. We have JAVA 2.0 as well as JAVA 1.0 on the m/c, & also classpath points to JAVA 2.0 still it is op on JRE 1.0. We guessed this problem bcos it shows runtime errors for JAVA 2.0 API specific code.